The second six entries can be used to enable a text shadow to be painted
with the icon labels. The offsets are in pixels. Setting them to 0 (the
defaults) will disable the shadows entirely. Again, the 'selected-'
versions apply to icons that have been selected with the mouse.

So the above entries might be what you're looking for.

Never cared for shadows myself, so that's probably why mine didn't have those lines. But like your screenshot!